Embryonic stem cells (ESCs) are pluripotent cells that have the capacity to self-renew indefinitely and to differentiate into all cell types of the body (Thomson, J. A. et al., Science 282 (5391): 1145-1147 (1998); Thomson, J. A. & Odorico, J. S., Trends Biotechnol 18 (2):53-57 (2000)). This ability provides hope that ESCs will one day be used to replace lost and damaged cells, and provide therapies beyond the reach of conventional drugs. However, to fully realize the clinical potentials of hESCs, chemically-defined, feeder- and animal product-free, robust culture conditions have to be established. Although several chemically-defined media have been reported (Yao, S. et al., Proc Natl Acad Sci USA 103 (18):6907-6912 (2006); Lu, J. et al., Proc Natl Acad Sci USA 103 (15):5688-5693 (2006); Ludwig, T. E. et al., Nat Biotechnol 24 (2): 185-187 (2006)), they are still largely unsatisfactory due to the suboptimal performance of cells in them. Especially under these conditions, when cells are passaged by trypsin to single cells, they undergo extensive cell death. A number of signaling pathways that mediate hESC self-renewal are known, including FGF, TGF-β, Wnt, etc. (James, D. et al., Development 132 (6): 1273-1282 (2005); Xu, R. H. et al., Nat Methods 2 (3):185-190 (2005); Beattie, G. M. et al., Stem Cells 23 (4):489-495 (2005); Greber, B., Lehrach, H., & Adjaye, J., Stem Cells 25 (2):455-464 (2007); Sato, N. et al., Nat Med 10 (1):55-63 (2004)). However, none of them appears to act as a survival factor in this process, the molecular mechanism of which being elusive.